Prevention of alcohol problems, particularly those associated with alcohol-related crashes, has been a major reason for the recent national campaign to make 21 the legal minimum purchase age for alcohol beverages in all states. The proposed research will provide important information on the prevention implications of differences in minimum drinking ages, and will provide an assessment of the degree of success that changes in minimum drinking ages have had in preventing or reducing alcohol related problems among young people. An important aspect of the research is that the prevention implications will be assessed for a variety of health-related behaviors, including self-reported drinking and driving, self-reported accidents involving drinking (which may not have been officially reported), use of alcohol and other psychoactive substances, frequency of excessive drinking, setting and circumstances of drinking, delinquent behavior, and school truancy. In addition to behaviors, related attitudes and beliefs will be investigated. These related attitudes and beliefs may well be important predictors of later change, and they may also be the intervening variables that account for behavior change. The analyses will take advantage of an existing dataset derived from an ongoing study involving (a) annual, nationally representative surveys of 15,000 to 19,000 high school seniors, and (b) annual follow-up surveys by mail of recent graduates. Thus, it will be possible to assess the effects of different minimum drinking ages on young people in the critically important age range from 17 to over 21. The research will examine closely the impact of changes in the years between 1976 and 1985 in minimum drinking age in 26 states for which both "before" and "after" data are available. Data from 13 other states where no change has occurred will be used for comparison purposes. By the time analysis and reporting will occur, data through 1987 will be available.